1. Field of the Invention
The present invention relates to an endoscope system in which illuminating light, which irradiates a subject from an endoscope, is emitted from light-emitting devices of a plurality of colors in a light source apparatus.
2. Description of the Related Art
As light source apparatuses for irradiating a subject with illuminating light from an endoscope, those using light-emitting devices such as LEDs have been proposed.
FIG. 10 is a diagram illustrating a configuration of a conventional endoscope system using LEDs as light sources.
An endoscope system 101 includes a scope 2, a light source apparatus 3, a video processor 4, a monitor 5 and a communication cable 6.
The light source apparatus 3 uses light-emitting devices that are a red LED (R-LED) 23r, a green LED (G-LED) 23g and a blue LED (B-LED) 23b as light sources, and includes an LED drive section 22 for supplying power to these LEDs to drive the LEDs, and a control section 21 that controls the LED drive section 22 based on information on a brightness of an object, which is to be inputted from the video processor 4 via the communication cable 6, to adjust intensities of light emitted from the LEDs of the respective colors.
Light emitted from the LEDs 23r, 23g and 23b in the light source apparatus 3 irradiates a proximal end of a light guide 11 in the scope 2 via an optical system. The illuminating light is conveyed inside the light guide 11, and irradiates a subject via a lens 12 for illumination, which is disposed at a distal end of an insertion portion of the scope 2.
An optical image of the illuminated subject is converted into an electrical signal by a CCD 13, which is an image pickup device disposed in a distal end portion of the insertion portion of the scope 2, and transmitted to the video processor 4.
Based on the electrical signal received from the CCD 13, the video processor 4 generates an image signal for providing display on the monitor 5, and generates brightness information and transmits the brightness information to the control section 21 in the light source apparatus 3 via the communication cable 6.
If red light emitted from the red LED 23r, green light emitted from the green LED 23g and blue light emitted from the blue LED 23b in the light source apparatus 3 are combined by, for example, the optical system in the light source apparatus 3, as illustrated in FIG. 2 relating to the present invention, white illuminating light WL can be generated.
However, even if frame-sequential illumination in which LEDs of respective colors are put on in turn at different times within one frame is performed as illustrated in FIG. 3 relating to the present invention instead of combination of light of respective colors via the optical system in the light source apparatus 3, an image displayed on a monitor as a result of combination performed in the video processor is an object image effectively provided by illumination with white illuminating light.
For example, in Japanese Patent Application Laid-Open Publication No. 2002-45330, paragraph [0044] discloses that an illumination unit 110 includes three light sources that emit white light Lw for normal image, excitation light Lr for autofluorescent image and reference light Ls for reference image, respectively, and paragraph [0013] discloses that if excitation light emitting means or reference light emitting means operates abnormally, illuminating light is emitted from illuminating light emitting means, image pickup means is switched to a state for picking up a normal image and display means is switched to a state for displaying a normal image.
The technique disclosed in Japanese Patent Application Laid-Open Publication No. 2002-45330 is a technique that if special illumination such as that with, e.g., excitation light fails, the illumination is switched to normal illumination.